Like HowStuffWorks on Facebook!

How Bone China Works


Bone China: Creating the Mold
This metal mold is prepped and ready to be filled. Notice the finished production plate mold on the right.
This metal mold is prepped and ready to be filled. Notice the finished production plate mold on the right.

The mold-making process is an integral part of china production.

Large metal master molds and plaster are used to make production molds. For dinner plates, the metal master molds look something like two automobile hubcaps sandwiched together.

To create a production mold, large bags of plaster are mixed with water and then funneled into a big mobile bucket that hangs overhead. Meanwhile, the metal master molds are prepped by spraying a soapy mixture inside. This residue will help with the release of the production mold later. The metal molds are lined up, one after the other, on three rows of tables. Each mold sits on top of something that looks like a lazy Susan (a disc-shaped piece of wood that spins).

The aerial bucket is used to fill the metal molds with thick, creamy plaster. This takes two people. One person pours while the other person spins the metal mold to make sure the plaster is distributed evenly.

Pouring the plaster mold
Pouring the plaster mold
Ready to be released
Ready to be released

It takes about 20 minutes for the plaster to set. A rubber mallet is used to loosen the plaster production mold by tapping along the outside of the metal. The mold is released when the two halves are pulled apart.

Air hoses are used to spray plaster bits out of the metal molds and to clean off the plaster molds, removing any excess plaster dust or particles. At a nearby table, someone inspects each mold and stamps it with the day's date. This helps track the number of times each mold is used.

Something like 300 molds are made in this factory every day. These molds are used in one of two ways: either with the clay pugs or with the slip. Let's check out pug molding first.